Festering Goblin

When Festering Goblin dies, target creature gets -1/-1 until end of turn.

Searing Rays

Choose a color. Searing Rays deals damage to each player equal to the number of creatures of that color that player controls.

Famished Foragers

When Famished Foragers enters, if an opponent lost life this turn, add {R}{R}{R}.
{2}{R}, Discard a card: Draw a card.

Haazda Snare Squad

Whenever Haazda Snare Squad attacks, you may pay {W}. If you do, tap target creature an opponent controls.

Glaciers

At the beginning of your upkeep, sacrifice Glaciers unless you pay {W}{U}.
All Mountains are Plains.

Jaya Ballard, Task Mage

{R}, {T}, Discard a card: Destroy target blue permanent.
{1}{R}, {T}, Discard a card: Jaya Ballard, Task Mage deals 3 damage to any target. A creature dealt damage this way can't be regenerated this turn.
{5}{R}{R}, {T}, Discard a card: Jaya Ballard deals 6 damage to each creature and each player.

Reckless Bushwhacker

Surge {1}{R} (You may cast this spell for its surge cost if you or a teammate has cast another spell this turn.)
Haste
When Reckless Bushwhacker enters, if its surge cost was paid, other creatures you control get +1/+0 and gain haste until end of turn.

Vulshok Heartstoker

When Vulshok Heartstoker enters, target creature gets +2/+0 until end of turn.

Chained Brute

Chained Brute doesn't untap during your untap step.
{1}, Sacrifice another creature: Untap Chained Brute. Activate only during your turn.

Wicked Guardian

When Wicked Guardian enters, you may have it deal 2 damage to another creature you control. If you do, draw a card.

Realmwright

As Realmwright enters, choose a basic land type.
Lands you control are the chosen type in addition to their other types.

Burrenton Forge-Tender

Protection from red
Sacrifice Burrenton Forge-Tender: Prevent all damage a red source of your choice would deal this turn.

Thornscape Familiar

Red spells and white spells you cast cost {1} less to cast.

Ambush Party

Grandmother Ravi Sengir

Flying
Whenever a creature an opponent controls dies, put a +1/+1 counter on Grandmother Ravi Sengir and you gain 1 life.

Invasion of Ulgrotha

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Ulgrotha enters, it deals 3 damage to any other target and you gain 3 life.

Invasion of Ulgrotha // Grandmother Ravi Sengir

Twisted Reflection

Choose one —
• Target creature gets -6/-0 until end of turn.
• Switch target creature's power and toughness until end of turn.
Entwine {B} (Choose both if you pay the entwine cost.)

Ghouls' Night Out

For each player, choose a creature card in that player's graveyard. Put those cards onto the battlefield under your control. They're black Zombies in addition to their other colors and types and they gain decayed. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.

Mind Extraction

As an additional cost to cast this spell, sacrifice a creature.
Target player reveals their hand and discards all cards of each of the sacrificed creature's colors.

Better Than One

A person outside the game becomes your teammate. (Choose any number of cards in your hand, on top of your library, or on the battlefield under your control. Those cards become your teammate's hand, library, and permanents, respectively.)